Abstract: During the external kinematic calibration of parallel kinematic machine (PKM) tools, in order to eliminate a few larger residual errors which possibly lie in the parameter identification based on the least square method, the min-max optimization method is presented. From the engineering sense of the residual errors of parameter identification, precision evaluation is oriented and min-max method directly controls the scope of residual errors. The experiment proves that the limitation of the least square method exists and the min-max method is effective to eliminate the limitation. The min-max method of parameter identification directly connects precision evaluation with kinematic calibration and can improve the total precision of PKM tools simply and cheaply.

Key words: Calibration, Least square method, Min-max optimization, Parameter identification, PKM tools